C4 - Acids and Redox Flashcards Preview

Year 12 - Chemistry > C4 - Acids and Redox > Flashcards

Flashcards in C4 - Acids and Redox Deck (18)
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1
Q

What happens when an acid dissolves in water?

A

It releases hydrogen ions as protons, H+, into the solution.

2
Q

What is a strong acid?

A

An acid which completely dissociates and releases all of its hydrogen atoms into a solution as H+ ions and completely ionises.
E.g. HCl

3
Q

What is a weak acid?

A

One which partially dissociates and doesn’t release all of its hydrogen atoms as H+ ions. It doesn’t ionise completely.
E.g. CH3COOH

4
Q

What is a base?

A

A metal oxide, hydroxide or carbonate

5
Q

What is an alkali?

A

A base which dissolves in water, releasing OH- ions into the solution.

6
Q

What is produced in the reaction of an acid and an alkali?

A

A salt and water

7
Q

What is produced in the reaction of an acid and a base?

oxide/hydroxide

A

A salt and water

8
Q

What is produced in the reaction of an acid and a carbonate?

A

A salt, water and carbon dioxide

9
Q

What is a titration?

A

A method used to measure the volume of one solution that reacts exactly with another solution, used for finding the concentration of a solution, identification of an unknown chemical or finding the purity of a substance.

10
Q

What is a standard solution?

How is it prepared?

A

A solution with a known concentration.

The solid is weighed accurately then dissolved in a beaker using less distilled water than will be needed to fill the volumetric flask.

Transfer the solution into the flask and rinse the final traces into the flask.

Fill the flask to the graduation line so the bottom of the meniscus lines up to the mark.

Invert it several times to mix it thoroughly.

11
Q

How is the acid-base titration procedure carried out?

A

Add a measured volume of one solution to a conical flask using a pipette and the other solution in the burette and record the initial reading.

Add a few drops of indicator to the flask solution.

Run the solution in the burette into the flask and swirl the flask until the colour changes to mark the end point.

The titre (volume of solution added) is calculated

A trial is carried out to find the approximate titre.

Repeat to find concordant results.

12
Q

How are titration calculations carried out?

A

Work out the amount, in moles, of the solute in the solution for which you known both the concentration and volume.

Use the equation to work out the number of moles of solute in the other solution.

Work out unknown info about the solute in the other solution.

13
Q

What is the oxidation number?

A

A measure of the number of electrons that an atom uses to bond with atoms of another element.
It is derived from a set of rules.

14
Q

What is the oxidation number for elements?

A

Always zero

15
Q

What are the oxidation rules for compounds and ions?

A

Each atom in a compound has an oxidation number

An oxidation number has a sign placed before the number

The sum of oxidation numbers = total charge

The most electronegative element is given their oxidation number first

16
Q
What are the oxidation numbers for:
O
H
F
Cl-
Na+
A
O -2
H +1
F -1
Cl- -1
Na+ +1
17
Q

What are the special cases/exceptions for oxidation numbers?

A

H in metal hydrides (-1)

O in peroxides (-1)

O bonded to F (+2)

18
Q

What occurs I redox reactions in terms of oxidation numbers?

A

Reduction is a decrease in oxidation number and gain in e-

Oxidation is an increase in oxidation number and loss of e-